Cyclic 3',5' adenosine monophosphate (cAMP) has been shown to be an important intracellular second messenger mediating the metabolic effects of several hormones in a variety of tissue. In the present study experiments are in progress in order to determine with greater precision the localization of phosphodiesterase and hormonal activation of adenyl cyclase-cAMP in neuronal and glial fractions from different areas of the brain. Likewise several studies indicate that the ability of some psychotropic drugs to influence adenyl cyclase-cAMP in the brain parallels their psychopharmacological potency in man and animals. Using tissue slices as well as neuronal and glial preparations studies are in progress to examine the effects of psychotropic drugs (phenothiazines, tricyclic antidepressants, monamine oxidase inhibitors, amphetamines and adrenergic blocking agents) on their ability to modify catecholamine activation of adenyl cyclase-cAMP. At present little is known as to which central metabolic processes are influenced by cAMP. Studies are planned to determine the role of cAMP on central glycogen breakdown, enzyme synthesis, lactate release and turnover of RNA protein and phospholipids. Moreover, studies are in progress in order to determine the role of adenyl cyclase in the molecular mechanisms underlying the phenomenon of adrenergic denervation supersensitivity. It is hoped that the present investigation will shed some light upon the relationship of adenyl cyclase to the catecholamine hypothesis of affective disorders.